ZZP has had that statement up there since they started their business what...over 5 years ago? I'm not saying you can't run a 3.4" with just a downpipe...I'm telling you it isn't safe unless you've got a way to scan for knock...and since headers are the price of a downpipe...they are always the best bet. You might take it as were bashing on you or your car...but were trying to help...many people here, including myself...have been through the whole chipped piston adventure...and it isn't fun. Trust me.
